In all these and similar cases, the primary cause of the waste lies in the decomposition of the felspar. Rain-water acts in removing the soluble portions, and the harder grains that remain, deprived of the cementing matrix, ere long crumble down and are washed off by the rains. In this way the rock insensibly moulders away, every frost loosening its structure, and every shower carrying away part of its substance. Among the many objects of interest along a rocky coast some of the more striking are certainly to be found in the curious and often grotesque forms assumed by the weathered cliffs. Above high-water mark and thus away from the dash of the waves, we can often trace the progress of decay among such sedimentary rocks as sandstones and conglomerates. Worn into holes and scars, projecting cusps and tapering pinnacles, or eaten away into the rude semblance of a human form, headless perchance, or into the shape of a huge table poised on a narrow pedestal, the rock affords an endless variety of aspects and a continual source of pleasure. If we chance to light upon any building constructed out of the sandstone of such cliffs, it is worth noting that the removal of the stone has not deprived it of its mouldering qualities; nay, that houses erected within the memory of people still living already begin to wear an aspect of venerable antiquity. I remember meeting with an interesting example in the case of an old castle built on a similar rocky coast-line. It stood on a little ness or promontory of dull red stone, washed on all sides save one by the wild sea. The walls, of which but a fragment remained, were built of a dark red sandstone; but the lapse of centuries had told sadly on their masonry. The stones rose over each other tier upon tier, corroded sometimes into holes and hollows, sometimes into a close honey-combed surface, but the mortar that had been used to cement them together still stood firm and protruded from between the tiers to show, by no doubtful or ambiguous sign, how silently yet how surely the wasting forces had been at work. The scutcheon over the only remaining gateway had been carved out of another kind of stone of a lighter colour and harder texture, and so its grim lions looked nearly as fresh and formidable as when first raised to the place of honour which they still occupied. In this case, as before, the decomposition was owing to the presence of a considerable proportion of soluble matter, which the rains of four centuries had carried away along with the loosened incoherent sandy grains.